To identify audience compositions, an audience measurement entity enlists a plurality of people to cooperate as panelists in an audience measurement panel. Media exposure and/or consumption habits of the panelists and/or demographic data associated with the panelists is collected and used to statistically project a size and demographic makeup of, for example, a television viewing audience as a whole. In some instances, automatic or passive measurement systems are supplemented with active measurement system(s) that require, for example, input from the panelists.